Neo-Deterministic Seismic Hazard Assessment in North Africa

J Seismol DOI 10.1007/s10950-013-9375-2

ORIGINAL ARTICLE

Neo-deterministic seismic hazard assessment in North Africa

T. Mourabit & K. M. Abou Elenean & A. Ayadi & D. Benouar & A. Ben Suleman & M. Bezzeghoud & A. Cheddadi & M. Chourak & M. N. ElGabry & A. Harbi & M. Hfaiedh & H. M. Hussein & J. Kacem & A. Ksentini & N. Jabour & A. Magrin & S. Maouche & M. Meghraoui & F. Ousadou & G. F. Panza & A. Peresan & N. Romdhane & F. Vaccari & E. Zuccolo

Received: 6 February 2013 /Accepted: 22 May 2013 # Springer Science+Business Media Dordrecht 2013

Abstract North Africa is one of the most earthquake- the earthquakes, the regional seismic hazard in North prone areas of the Mediterranean. Many devastating Africa is assessed using the neo-deterministic, multi- earthquakes, some of them tsunami-triggering, inflicted scenario methodology (NDSHA) based on the compu- heavy loss of life and considerable economic damage to tation of synthetic seismograms, using the modal sum- the region. In order to mitigate the destructive impact of mation technique, at a regular grid of 0.2×0.2°. This is

Electronic supplementary material The online version of this article (doi:10.1007/s10950-013-9375-2) contains supplementary material, which is available to authorized users.

T. Mourabit : A. Cheddadi M. Chourak Département de Géologie, Université Abdelmalek Essaadi, OLMAN-RN, Faculté Pluridisciplinaire, Nador, BP. 416, 90001 Tangiers, Morocco Université Mohamed I, Oujda, Morocco

K. M. Abou Elenean : M. N. ElGabry : H. M. Hussein M. Hfaiedh National Research Institute of Astronomy and Geophysics, Nuclear Power Project, Société Tunisienne de l’Electricité et NRIAG, 11421 Helwan, Cairo, Egypt du Gaz, STEG, Tunis, Tunisia

A. Ayadi : A. Harbi (*) : S. Maouche : F. Ousadou J. Kacem Centre de Recherche en Astronomie, Astrophysique et Faculté des Science de Sfax, Sfax, Tunisia Géophysique, CRAAG, BP. 63, Bouzaréah, Algiers, Algeria A. Ksentini : N. Romdhane e-mail: [email protected] Ecole Nationale des Ingénieurs de Tunis, Tunis, Tunisia

A. Harbi N. Jabour e-mail: [email protected] Centre National de Recherche Scientifique et Technique, Rabat, Morocco D. Benouar Faculté de Génie Civile, Université de Bab Ezzouar A. Magrin : G. F. Panza : A. Peresan : F. Vaccari (USTHB), BP. 32, El Alia, ESP Section, SAND Group, The Abdus Salam International Algiers, Algeria Centre for Theoretical Physics, ICTP, Strada Costiera 11, 34014 Trieste, Italy A. Ben Suleman Tripoli University, Tripoli, Libya A. Magrin : G. F. Panza : A. Peresan : F. Vaccari : E. Zuccolo M. Bezzeghoud Dipartimento di Matematica e Geoscienze, Università di Evora University, Evora, Portugal Trieste, Via Weiss, 4, 34128 Trieste, Italy J Seismol the first study aimed at producing NDSHA maps of 2004). Generally, North Africa has experienced moder- North Africa including five countries: Morocco, ate earthquakes. However, the region remains vulnera- Algeria, Tunisia, Libya, and Egypt. The key input data ble due to the shallow character of its seismicity, the for the NDSHA algorithm are earthquake sources, poor mechanical properties of its soil and local site seismotectonic zonation, and structural models. In the conditions, and the consequent strength of the ground preparation of the input data, it has been really important shaking. The damaging earthquakes of Agadir, Morocco, to go beyond the national borders and to adopt a coher- in 1960 (Mw=5.9,1,5000peoplewerekilled);ElAsnam, ent strategy all over the area. Thanks to the collaborative Algeria, in 1980 (Mw=7.3, 3,000 people were killed); efforts of the teams involved, it has been possible to Cairo, Egypt, in 1992 (Mw=5.8, 541 peoplewerekilled); properly merge the earthquake catalogues available for Zemmouri, Algeria, in 2003 (Mw=6.8,2,278peoplewere each country to define with homogeneous criteria the killed); and Al Hoceima, Morocco, in 2004 (Mw=6.4, seismogenic zones, the characteristic focal mechanism 600 people were killed) resulted in damages worth US associated with each of them, and the structural models $11.5 billion (Benouar 2005). used to model wave propagation from the sources to the Rapid urbanization; development of critical structures sites. As a result, reliable seismic hazard maps are pro- and lifelines, such as dams and oil facilities; industriali- duced in terms of maximum displacement (Dmax), max- zation of cities; and the concentration of populations, imum velocity (Vmax), and design ground acceleration. living or settling in hazardous areas, are all matters of growing concern. Indeed, the recent social and economic Keywords North Africa . Seismotectonics . development exposed to earthquake hazards implies fu- Deterministic seismic hazard . Seismogenic ture heavier loss of life and economic damage, unless zone . Design ground acceleration reliable preventive actions are enforced following the rapid rise of interest about environment concerns and increased official and public awareness about earthquake 1 Introduction hazard in Northern Africa. The assessment of seismic hazard in North Africa is Earthquake hazard in Northern Africa constitutes a relatively new and started at the end of the last century. It constant threat to human life and property, causing consists of regional and local studies using mainly the major economic losses and disruption. The past few probabilistic approach (probabilistic seismic hazard ap- years have seen an unprecedented level of damage from proach, PSHA; El-Sayed et al. 1994; Benouar 1996; seismicity in active regions of North Africa, which has Benouar et al. 1996; Hamdache et al. 1998; Hamdache focused the attention of scientists and local communities and Retief 2001; Giardini et al. 1999; Pelaez et al. 2003, on geohazards. The May 2003 Zemmouri earthquake 2005, 2006, 2007; Hamouda 2011; Wyss et al. 2012).

(Mw=6.8) that occurred east of the city of Algiers is the These studies severely underestimate the values of the largest felt since that in February 1716 (I0=IX EMS). In expected peak ground acceleration (PGA), as in the February 2004, the city of Al Hoceima and the Rif cases of the Zemmouri, Algeria, earthquake in 2003 Mountains of Morocco were struck, once again, by a (observed=0.3–0.4 g, PSHA=0.08–0.16) and Al large earthquake (Mw=6.4), 10 years after the May 1994 Hoceima, Morocco, earthquake in 2004 (observed=0.2– (M=6.0) event. The city of Cairo was struck in October 0.3 g, PSHA=0.08–0.16).

1992 by an Mw=5.8 magnitude earthquake, which In order to carry out a realistic and reliable estimate of caused large damage. In 1935, the Syrte region in the seismic hazard in some North African countries Libya experienced an M=6.9 earthquake with severe (Egypt, Algeria, and Morocco), some authors (Aoudia et damage (Suleiman and Doser 1995; Suleiman et al. al. 2000;ElSayedetal.2001;Vaccarietal.2001;Harbiet al. 2007)usedtheneo-deterministic,multi-scenarioproce- M. Meghraoui dure (NDSHA) that takes into account the physical pro- Institut de Physique du Globe, UMR 7516, 5 rue R. cess generating the earthquakes as well as wave propaga- Descartes, Strasbourg, France tion in a realistic medium, and it is particularly suitable when earthquake recordings are scarce. G. F. Panza Institute of Geophysics, China Earthquake Administration, In this paper, after an introduction to the seismotectonic Beijing, China context of North Africa, we (1) briefly describe the J Seismol

NDSHA (Panza et al. 2001, 2012;Zuccoloetal. seismicity, active faulting, and structural models in 2011)methodadoptedfortheassessmentofseis- each seismogenic zone; and (4) present the results mic hazard in North Africa (NAF) in view of the obtained as maps of the distribution of maximum limited strong ground motion data; (2) describe the displacement (Dmax), maximum velocity (Vmax), input information (earthquake catalogue, earth- and design ground acceleration (DGA). These the- quake sources, and focal mechanisms), on the basis matic maps about earthquake hazard in NAF con- of which we delineate 39 zones in NAF; (3) provide two stitute important basic information necessary for the databases—(a) the fault-plane solutions of the NAF sustainable social and economic development of North region (Fig. 1a, b) and (b) the available data concerning Africa.

Fig. 1 Seismicity with M>4.5 of Northern Africa and adjacent Focal mechanisms are from CMT-Harvard and mednet areas. a Maghreb. b Egypt–Libya seismicity data (1900–2008) (Meghraoui and Pondrelli 2012) and Hussein (pink, in are from the NAF1.0 earthquake catalogue (Peresan et al. 2009). preparation) J Seismol

2 Seismotectonics and crustal deformation Atlas has accommodated 17–45 % of the total African– in Northern Africa Eurasian plate convergence since the Early Miocene, whereas the majority of the plate convergence is accom- Northern Africa is located in a complex tectonic system modated in the Rif–Betic–Alboran region (Gueguen et al. that results from the interaction between a seismically 1998;Gomezetal.2000). The Maghreb region experi- active plate boundary (Africa/Eurasia) and fault sys- enced many destructive or damaging earthquakes, some of tems. The African plate has been divided into six differ- them triggering tsunami, in historical and recent times as ent seismotectonic provinces, based mainly on the ac- well (Turki 1990;Benouar1994;Ayadietal.2003;El tive tectonics, present-day continental deformation, and Mrabet 2005;Harbietal.2003a, 2007, 2010, 2011; background seismicity (Meghraoui 2011a, b). Two of Maouche et al. 2008;Suleimanetal.2004;Tahaytetal. these provinces concern North Africa: the Northwest 2008;seeTable1). African fold-and-thrust belt and the Northeast African tectonic zones of Libya and Egypt. 2.2 The Northeast African tectonic zones of Libya and Egypt or the southeastern Mediterranean region 2.1 The Northwest African Atlas Mountains and Maghrebides fold-and-thrust belts This region (Fig. 1b) is limited by the Gulf of Aqaba and Red Sea in the East. This eastern region of North This region includes Morocco, Algeria, and Tunisia Africa is also the corner contact between the African (Fig. 1a). The deformation in the Maghreb region is plate, the Arabian plate, and the Eurasian/Anatolian evident in the currently active Atlas system and the plate. These plates are involved in the geodynamic Maghrebides (Dewey et al. 1989; Udias and Buforn reconstructions of the southern part of eastern 1991; Morel and Meghraoui 1996; Frizon de Lamotte Mediterranean (Abou Elenean 2007). The plate tec- et al. 2000; Gomez et al. 2000) and the 4- to 6-mm/year tonic models indicate that the African plate is moving NW–SE plate convergence (Nocquet and Calais 2004; northward relative to the Eurasian plate at a slip rate of Fadil et al. 2006; Serpelloni et al. 2007; Koulali et al. ∼6 mm/year (Salamon et al. 2003; Mahmoud et al. 2011). The Atlas system is an intraplate inversion struc- 2005; Reilinger et al. 2006), while the Arabian plate is ture, whereas the Maghrebides are the southwestern moving north–northwest relative to Eurasia at a rate of prolongation of the Apennines–Maghrebides subduc- about ∼18 mm/year (Wdowinsky et al. 2004; tion zone whose southern arm in northwestern Africa Reilinger et al. 2006). These movements cause crustal is overprinted by the relative Africa–Eurasia conver- spreading along the axis of the Red Sea and left-lateral gence (Gueguen et al. 1998). Seismicity in this region slip along the Dead Sea transform zone. The differen- results from the NNW/SSE-trending plate convergence tial motion between Africa and Arabia (∼12 mm/year) of Africa toward Eurasia (Table 1; Benouar 1994; Harbi is considered to be taken up predominantly by a left- et al. 2010; Tahayt et al. 2008). The focal mechanisms of lateral motion along the Dead Sea transform fault recent earthquakes display consistent WNW/ESE- and (McClusky et al. 2003; El Fiky 2000). The global NW/SE-trending reverse and right-lateral strike slip, model of plate tectonics suggest NNW convergence respectively, in the Gulf of Cadiz (Buforn et al. 1995). between the African and Eurasian plates in the north Furthermore, the seismotectonic characteristics show of Libya (DeMets et. al. 1990), but focal mechanisms NE/SW-trending left-lateral strike slip in the Rif region for Libyan earthquakes suggest a rapid change in the related to the 26th May 1994 (Mw=6.0) and 28th orientation of maximum compressive stress (NNW to February 2004 (Mw=6.4) Al Hoceima earthquakes NE–SW) within the onshore section of the African (Calvert et al. 1997; Buforn et al. 1997; Bezzeghoud plate. There also appears a significant change in the and Buforn 1999; Çakir et al. 2006; Akoglu et al. 2006); stress regime across Libya, with NNW/SSE-trending NE/SW-trending thrust faulting across the Tell Atlas as normal faulting more common in eastern Libya. The indicated by the 10th October 1980 El Asnam earth- large number of strike-slip earthquakes in western quake (Ms=7.3; Ouyed et al. 1981; Ruegg et al. 1982); Libya suggests that the existing normal faults are the 29th October Tipasa earthquake (Mw=6.0;Meghraoui being reactivated in a stress regime related to the 1991); and the 21st May 2003 Zemmouri earthquake (Mw convergence of the African plate and the Eurasian =6.8;Meghraoui etal. 2004). Shortening of the Moroccan plate (Suleiman and Doser 1995). Near Sicily, the J Seismol

Table 1 Significant, moderate, and large earthquakes in North Africa (earthquakes mentioned in this table may be subject to revision)

Date Site Intensity or Observations References magnitude

600BC Thebes, Egypt 6.1 Maamoun et al. (1984) 28BC Thebes, Egypt 6.1 Maamoun et al. (1984) 262 E. Mediterranean, XII Cyrene destroyed. After an Guidoboni et al. (1994); Libya extensive destruction by the Vita-Finzi (2010) earthquake, Cyrene was rebuilt by the general Probus, who renamed it after the reigning emperor (Claudius II Gothicus) in AD268 320 Alexandria, Egypt 6.0 Maamoun et al. (1984) 365 Leptis Magna, Sabratha, XII Cyrene destroyed Polidori et al. (1999); Libya Stiros (2001) 410 or 412 Utique, Tunisia X Utique destroyed, many aftershocks Sieberg (1932); Rothé (1970) during a week 704 Murzk (Sabha), Libya XII Spurious, mislocated in Libya Suleiman et al. (2004) 796 April Gulf of Aqaba 6.0 Maamoun et al. (1984) 854 or 855 Kairouan, Tunisia X 13 villages destoyed Ambraseys (1962); Rothé (1970) 856 December Tunis, Tunisia X 45,000 victims Ambraseys (1962); Rothé (1970) 956 January 01 Alexandria, Egypt 6.0 Maamoun et al. (1984) 1068 March 18 Gulf of Aqaba IX Zilberman et al. (1998) 1079 October Morocco IX El Mrabet (2005) 1111 August 31 Lower Egypt 7.2 Ambraseys et al. (1994a) 1365 January 3 Algiers, Algeria X Sea wave of ∼2 m Harbi et al. (2007) 1624 Fez, Morocco IX-X El Mrabet (2005) 1716 February 03 Algiers-Douéra, Algeria IX 20,000 victims Harbi et al. (2007) 1719 July Morocco VIII El Mrabet (2005) 1731 Agadir, Morocco IX El Mrabet (2005) 1754 October Gulf of Suez 6.6 Ambraseys et al. (1994a) 1755 November 27 Meknes, Morocco Destructive, thousands of victims El Mrabet (2005) 1758 January Constantine and Tunis VIII Most of the houses of Tunis “Journal Historique sur la destroyed, thousands of victims matière du temps” of March 1758; Vogt (1993) 1790 October 09 Oran, Algeria X 2,000 victims Roussel (1973) 1811 Libyan–Egyptian boarder VIII Maamoun et al. (1984) 1819 Mascara, Algeria IX Roussel (1973) 1825 March 2 Blida, Algeria X 7,000 victims Roussel (1973) 1847 August 7 Cairo, Egypt 5.8 Hundreds of victims Maamoun et al. (1984) 1856 August 22 Djidjelli, Algeria 6.6 Widely felt in the Mediterranean, Harbi et al. (2011) tsunami on 21 and 22 August 1867 January 2 Mouzaia, Algeria X–XI Roussel (1973) 1869 November 9 Biskra, Algeria VIII Harbi et al. (2003a) 1885 December 3 M’sila, Algeria IX Harbi et al. (2003a) 1881 June 27 Gabès, Tunisia VI Many shocks at Gabès and in Sieberg (1932); Vogt (1993), southern Tunisia the French consul of Gabès 1891 January 15 Gouraya, Algeria 6.0 Maouche et al. (2008) 1910 June 24 Aumale, Algeria 6.6 Benouar (1994) 1920 February 25 Thibar, Tunisia VIII Important event, widely felt at Rothé (1970) Tunis J Seismol

Table 1 (continued)

Date Site Intensity or Observations References magnitude

1926 June 226 North Libya 7.1 Ambraseys et al. (1994b) 1935 April 19 Al-Qadahia, Libya 6.9 Suleiman and Doser (1995) 1954 September 9 Orleansville, Algeria 6.7 1,409 victims Benouar (1994) 1955 September 12 Alexandria, Egypt 6.0 Maamoun et al. (1984) 1960 February 29 Agadir, Morocco 5.6 El Mrabet (2005) 1969 March 31 Shedwan, Egypt 6.1 Maamoun et al. (1984) 1980 October 10 El-Asnam, Algeria 7.3 3,000 victims Benouar (1994) 1994 August 18 Mascara, Algeria 5.9 171 victims Benouar et al. (1994) 1992 October 12 Cairo, Egypt 5.8 541 victims Abou El Enean et al. (2000) 2003 May 21 Zemmouri, Algeria 6.8 2,278 victims, tsunami on the Ayadi et al. (2003) Balearic coast 2004 February 24 El-Hoceima, Morocco 6.4 600 victims Tahayt et al. (2009)

direction of plate convergence is estimated to be motion with an annual probability of exceedance, cal- approx. North–South (Serpelloni et al. 2007). An al- culated from a mathematical model (not a physical one) ternative view has been proposed by Corti et al. (2006) and based on the statistical relationships of earthquake who suggested that Red Sea rift is transferred to west- and ground motion. In PSHA, the hazard maps are only ern Egypt and Libya, entering into the active rifting of defined in terms of PGA, neglecting the relevance of the Sicily channel. Significant earthquakes, some of other factors, like, for instance, ground shaking dura- them widely felt and causing widespread damage to tion. The spectral properties of ground shaking, ex- local houses and public buildings, affected the south- tremely important for the correct evaluation of the dam- eastern Mediterranean region (Maamoun et al. 1984; aging potential of earthquakes, are either neglected by Ambraseys et al. 1994a; Zilberman et al. 1998; see PSHA or are treated in an overly simplified way, usually Table 1). reading the spectral acceleration on a response spectrum whose artificial shape is associated with classes of soil types. Well-documented criticisms have been expressed 3 Methodology on the probabilistic method by many authors (e.g., Krinitzsky 1998; Castaños and Lomnitz 2002; Klügel By definition, seismic hazard describes a natural phe- 2007; Wang 2011; Kossobokov and Nekrasova 2012) nomenon associated with an earthquake, such as who evidenced some relevant limits in the models and in ground shaking, fault rupture, tsunami, liquefaction the basic assumptions. Several issues related with the rockfall, landslide, etc. It is generally quantified by PSHA approach and possible alternatives are discussed three parameters: (a) the level of severity expressed by in the Topical Volume of Pure and Applied Geophysics intensity I, magnitude M, and peak ground accelera- (Panza et al. 2011) and in Panza et al. (2012), where the tion and (b) spatial (occurrence site) and (c) temporal NDSHA method is described in detail. (occurrence frequency) characteristics. NDSHA allows overcoming the shortcomings of A thorough discussion of the different approaches PSHA (e.g., Wyss et al. 2012), particularly where available for seismic hazard assessment is beyond the earthquake catalogue completeness is poor and strong purposes of the present work. The PSHA method is earthquakes are expected (Zuccolo et al. 2011). In commonly used for seismic hazard assessment and is NDSHA, seismic hazard is defined as the maximum widely described in the literature (Cornell 1968; ground motion from a single earthquake or from a set Bommer and Abrahamson 2006 and references therein). of earthquakes, including maximum credible earth- It has been the subject of intensive debate in recent quake, calculated considering the available physical years. In PSHA, seismic hazard is defined as ground knowledge on earthquake sources and wave J Seismol propagation processes by means of deterministic to effective peak acceleration, which is defined as models. At the regional level, the ground shaking the average of the maximum ordinates of the elas- scenario is defined through the computation of tic acceleration response spectra within the period synthetic seismograms generated from the set of range from 0.1 to 0.5 s, divided by a standard potential sources distributed in the active factor of 2.5, for 5 % damping (Panza et al. seismogenic zones recognized in the studied area. 2003, 2013). At each node of the grid, not only To define the sources, the NDSHA procedure the peak values are available, generated by the makes use of information about the space distribu- nearby earthquake sources, but also the full time tion of large-magnitude earthquakes (M>5), which series from which the peak values are extracted. can be defined from historical, instrumental, and Those time series can be taken as the seismic geological observations. The seismograms are effi- input by civil engineers in the design of seismo- ciently computed with the modal summation tech- resistant structures. Therefore, one of the advan- nique (Panza 1985;Florschetal.1991). tages of NDSHA is the possibility of obtaining a Hypocentral depth is taken as a function of mag- set of earthquake scenarios and simulating the nitude (10 km for M<7, 15 km for M≥7). As associated synthetic signals without having to wait specified by Panza et al. (2001), keeping the hy- for a strong event to occur. pocentral depth fixed (for classes of magnitude) NDSHA has been successfully tested worldwide and shallow is important due to the large errors (Panza et al. 1996, 1999, 2002; Alvarez et al. 1999; generally affecting the hypocentral depth for his- Aoudia et al. 2000; Bus et al. 2000; Markusic et al. torical events reported in the earthquake cata- 2000; Zivcic et al. 2000; El-Sayed et al. 2001; Vaccari logues. Layered anelastic models are considered et al. 2001; Parvez et al. 2003; Zuccolo et al. 2011) for wave propagation, which are representative of and has proved its efficiency, particularly for recent the average properties of the crust and upper man- earthquakes (e.g., the Zemmouri-Boumerdes, Algeria, tle along the considered source site paths. From 2003 and Gujarat, India, 2011 events), where the the set of complete synthetic seismograms, various PSHA method has failed to predict the level of ground engineering parameters can be extracted and motion observed. Its application to the NAF region is mapped on a grid that covers the investigated area. shown in Section 5. Typically, they are the maximum displacement

(Dmax), maximum velocity (Vmax)andDGA. DGA is obtained by computing the response spec- 4 Data trum of each synthetic signal for periods of 1 s and longer (the periods considered in the genera- To model ground motion using the modal summation tion of the synthetic seismograms, consistent with technique and compute realistic synthetic seismograms the detail of knowledge about earthquake sources (Panza et al. 2001), the information required consists of and propagation media). The spectrum is extended (a) the level of seismicity and the distribution of maxi- at frequency higher than 1 Hz using the shape of mum observed magnitude inferred from the earthquake the design response spectrum for the bedrock, catalogue, which is the most essential and important which defines the normalized elastic acceleration input parameter; (b) the available knowledge of the response spectrum of the ground motion, for 5 % physical process of earthquake generation (seismogenic critical damping; for details, see Panza et al. source zones); and (c) structural models to be used in the 1996). DGA is comparable to the PGA since an wave propagation in anelastic media. The input data infinitely rigid structure (i.e., a structure having a used for the NAF region are briefly described below. natural period of 0 s) moves exactly like the ground (i.e., the maximum acceleration of the 4.1 The earthquake catalogue structure is the same as that of the ground, which is the PGA). This is why PGA has been used over An updated unified and homogeneous catalogue has the years to provide a convenient anchor point for been jointly compiled and prepared specifically for the the design spectra specified by various regulatory seismic hazard assessment in North Africa: “the agencies. Moreover, DGA is practically equivalent NAF1.0 earthquake catalogue” (Peresan et al. 2009). J Seismol

The unified catalogue has been compiled following the NEIC and ISC global catalogues as reference data two main phases: (a) national catalogue revision and sets, so as to assess the spatial completeness level of internal homogenization and (b) assessment, compar- each national catalogue. This analysis permits ison, and merging of the different national catalogues outlining the territory where the different data set into a unified data set. A detailed description of the should be used. Finally, the national catalogues are input data and of the merging procedure is provided in merged together and possible duplicated records, par- Peresan and Ogwari (2010). ticularly at the boundaries between different countries, A number of available sources were considered, are carefully identified and eliminated. The resulting including (1) catalogues and bulletins of national and unified catalogue, which is complete for magnitudes international centers (CNRST, Morocco; CRAAG, M≥5.0 at least since 1900, is updated using the ISC Algeria; INM, Tunisia; LCCRS, Libya; NRIAG, (2012) global catalogue since 1994. Egypt; IGN, Spain; INGV, Italy; NEIC, ISC, The NAF1.0 earthquake catalogue includes for the EMSC); (2) recent local and regional earthquake cat- first time the whole data compiled separately so far in alogues assembled by authors (Cherkaoui 1991; the NAF region. Ongoing research is devoted to the Benouar 1994; El Alami et al. 2004; Pelaez et al. further improvement of the completeness and magni- 2007; Hussein et al. 2008; Harbi et al. 2010); and (3) tude homogeneity for this unified data set, accounting specific works on historical seismicity (Turki 1990; for recent studies about historical seismicity and new Ambraseys et al. 1994a, b; Suleiman and Doser 1995; incoming data. The present-day completeness thresh- Harbi et al. 2003a, 2007, 2011; Suleiman et al. 2004; old of the NAF1.0 earthquake catalogue severely El Mrabet 2005; Maouche et al. 2008). The input data questions the validity of the existing and future for the compilation of NAF1.0 consist essentially of PSHA results in NAF countries. the Egypt, Libya, Tunisia, Algeria, and Morocco national catalogues, which are described in some detail 4.2 Earthquake sources: seismogenic zones and focal in Peresan and Ogwari (2010). In most cases, the mechanisms national catalogues contain Ms, Mb, and Ml magnitudes that, for historical events, were derived from Thirty-nine seismogenic zones were delineated in intensities. In the Algeria catalogue, magnitude ho- North Africa (Fig. 2a) from causal relationships mogenization was performed in terms of Ms by established between geological structures and earth- Benouar (1994) and Harbi et al. (2010). The moment quakes. We first defined the seismogenic zones for magnitude, which is currently considered an appropri- each NAF country and then properly merged the zones ate quantification of earthquake size, is reported in at the boundaries for the definition of the new unified some national catalogues only for the largest recent seismotectonic zoning. This delineation of the events. Some national catalogues, such as the seismogenic zones of the NAF region is presented Egyptian catalogue (Hussein et al. 2008) and the here for the first time for Tunisia and Libya. In Moroccan catalogue (Pelaez et al. 2007), provide mo- Algeria, Egypt, and Morocco, assessment of earth- ment magnitude for all earthquakes. The homogeniza- quake hazard using NDSHA has already been tion of available magnitude estimates in terms of Mw performed by Aoudia et al. (2000), El-Sayed et al. was performed using specifically defined empirical (2001), and Vaccari et al. (2001), respectively. relations. When different magnitude estimates are Starting from the first definition of seismotectonic present for the same event, to be conservative, we source zones in Algeria by Aoudia et al. (2000) and choose the maximum magnitude. Only earthquakes our current state of knowledge and understanding of with magnitude M≥3.0 are included in the catalogue. the seismicity and tectonics of the area, we properly To allow for an appropriate merging of national data modified the geometry of the zones, taking into ac- sets, a preliminary analysis is performed for each count the new elements provided by the study of (a) individual catalogue by evaluating earthquake distri- historical earthquakes of eastern Algeria and the bution versus magnitude and time as well as by ana- Algiers region (Harbi et al. 2003a, b, 2007; Maouche lyzing the frequency–magnitude distribution for dif- et al. 2008; Harbi et al. 2011) and (b) recent earth- ferent time spans. Spatial coverage is evaluated as quakes: Ain Temouchent 1999, Mw=5.7 (Belabbès et well, according to Kossobokov et al. (1999) and using al. 2009a); Beni Ourtilane 2001, Mw=5.7 (Bouhadad J Seismol

Fig. 2 a North African seismogenic zones (the order of zone numbering is arbitrary from the west to the east). b Average focal mechanisms assigned to each

et al. 2003); Zemmouri 2003, Mw=6.8 (Ayadi et al. A similar revision, based on several geological and 2003; Meghraoui et al. 2004; Alasset et al. 2006; geophysical studies, has been carried out for Egypt Laouami et al. 2006; Ayadi et al. 2008; Belabbès et (Cochron et al. 2005; Korrat et al. 2005) and Morocco al. 2009b); and Laalam 2006, Mw=5.2 (Beldjoudi et (Ait Brahim et al. 2002; Michard et al. 2002; Gracia et al. 2009). al. 2003; Baptista et al. 2003; Ait Brahim et al. 2004;

Fig. 3 Regional polygons characterized by an ASM representing the lithospheric properties at a regional scale J Seismol

Fig. 4 Average structural models defined in each zone J Seismol

Fig. 5 Discretization of the epicentral punctual distribution into cells. In each cell, only the maximum event magnitude is retained and represented in a graphical magnitude range classification

Biggs et al. 2006; Tahayt et al. 2008). However, the seismogenic zone will have the properties of the seismogenic zones for Morocco and Egypt were representative focal mechanism assigned to the zone completely revised and a new version is given here. (Fig. 2b). The NAF region is dominated by reverse Most of the seismogenic NAF zones are described in and strike-slip faults in the Maghreb, in agreement details in the Electronic supplementary material (ESM) with the NS shortening along the Africa–Eurasia Online Resource. The seismogenic zones are very dense boundary, while normal faults are present in Egypt along the collision plate boundary, i.e., along the Atlas in relation to Red Sea opening. range (Morocco, Algeria, and Tunisia) and Eastern Egypt along the Red Sea, whereas some gaps may be 4.3 Structural models observed in the Saharan Atlas, Libya, and in southern Egypt (Fig. 2a). Regional polygons define structural models that sepa- We adopted published fault plane solutions derived rate areas characterized by different lithospheric prop- from the literature (e.g., Girardin et al. 1977; Hatzfeld erties. For Morocco, Algeria, and Egypt, the initial 1978; Buforn et al. 1988; Medina and Cherkaoui boundaries of the polygons are adopted from Vaccari 1991; Bezzeghoud and Buforn 1999; Buforn et al. et al. (2001), Aoudia et al. (2000), and El-Sayed et al. 2004; Abou Elenean and Hussein 2007; Abou (2001), respectively, and have been further modified Elenean et al. 2000; Hussein et al. 2006; Abou on the basis of the results given in more recent studies Elenean 2007) and CMT solutions to define source as reported above and in the ESM Online Resource. mechanisms. A representative fault mechanism, which The structural models of the media beneath the site of is generally associated with the largest event, is de- interest are represented by a number of flat layers with fined for each seismogenic zone. When no reported different thicknesses, densities, P- and S-wave phase mechanism is available, we assigned the zone a typical velocities, and attenuation (corresponding Q values). fault mechanism, compatible with the tectonic regime In order to propose a suitable structural model for all and the geology of the area. In the computation of the North Africa, all available geophysical and geological synthetic seismograms, all the sources belonging to a information is considered here (Marillier 1981; El-

Fig. 6 Seismogenic sources corresponding to the inter- section between windows smoothed seismicity and the predefined 36 seismogenic zones. Only the considered events inside the seismogenic sources are used in the computations J Seismol

Fig. 7 Maximum computed displacement distribution map

Gamili 1982; Cherkaoui 1991; Marzouk 1995; synthetic seismograms. Data are graphically represented Barazangi et al. 1996; Nyblade et al. 1996; Du et al. and symbols are associated with magnitude ranges 1998; Calvert et al. 2000a, b; El Mozoughi and Ben (Fig. 5). In most of cases, the smoothing obtained by Suleman 2000; Lee et al. 2001; Xie and Mitchell considering just the discretized cells is not sufficient. A 1990). Since the computation is aimed at a first-order centered smoothing window is then considered so that seismic zoning, the structural models do not explicitly earthquake magnitudes are analyzed not only in the account for local site effects, but are representative of central cell but also in the neighboring ones. The distri- regional average properties (bedrock) within each bution of the maximum magnitude given by the inter- polygon (Fig. 3). In the present study, the NAF region section between the smoothed seismicity and the geom- is subdivided into nine average structural models etry of the seismogenic zones appears quite reasonable (ASM; Fig. 4). (Fig. 6). Each colored dot in Fig. 6 represents a source, for which the synthetic seismograms will be computed using the modal summation technique (Panza 1985; 5 Computation and results Florsch et al. 1991) for sites located within a distance of 150 km. Sites are defined on a grid with step 0.2×0.2° The NDSHA approach is applied here at the NAF scale that covers the NAF region. Looking at the structural by computing seismograms at the nodes of a grid with regional polygons of Fig. 3 in the computation of the the desired spacing. Earthquake epicenters reported in synthetic seismograms, lateral heterogeneities are taken the catalogue are grouped into 0.2×0.2° cells, assigning into account in a rough way: if the source site path to each cell the maximum magnitude recorded within it. crosses one or more boundaries between adjacent struc- A smoothing procedure is then applied to account for tural models, the signal is computed assuming the model errors in the location of the source and for its extension of the site as representative of the whole path. in space (Panza et al. 2001). Only cells located within At this stage, we do not have a complete database the seismogenic zones are retained for the definition of of the resonance period of buildings in all the NAF the seismic sources that are used to generate the areas. The synthetic signals are computed for an upper

Fig. 8 Maximum computed velocity distribution map J Seismol

Fig. 9 Maximum computed DGA distribution map

frequency content of 1 Hz, which is consistent with obtained in Tangiers region (NW of Morocco) and in the level of detail of the regional structural models, Fes city at Rif Mountain and the Middle Atlas margin. and the point sources are scaled for their dimensions They are also obtained in Libyan shores in Benghazi using the spectral scaling laws proposed by Gusev and Tripoli cities and in Alexandria city in the (1983), as reported in Aki (1987), and are scaled Egyptian territory. according to the smoothed magnitude distribution. The predominant factor in terms of seismic hazard The seismograms are computed for a hypocentral seems to be in general linked to the occurrence of depth, which is a function of magnitude (10 km for moderate-sized earthquakes at short distances (i.e.,

M<7, 15 km for M≥7), but it is also possible to assign the Agadir 1960 earthquake, Mw=5.9; the Alhoceima to each source an average depth determined from the 1994 and 2004 earthquakes, Mw=5.7 and 6.4, respec- analysis of the available catalogues. tively; the Al-Asnam 1980 and Zemmouri 2003 earth-

The maps of seismic hazard obtained for the whole quakes, Mw=7.3 and 6.8, respectively; the Cairo earth- NAF area are shown in Figs. 7, 8, and 9 for Dmax, quake in 1992, Mw=5.8) rather than to strong earth- Vmax, and DGA, respectively. The Fourier spectra of quakes that are known to occur at larger distances displacements and velocities show that an upper fre- along the Atlantic Azores islands in the western quency limit of 1 Hz is sufficient to take into account NAF area or in the western part along northern Red the dominant part of seismic waves (Panza et al. Sea and the Gulf of Suez (e.g., the Shedwan earth- −1 1999). Values between 8 and 60 cm s are obtained quake in 1969, Mw=6.9; the Gulf of Aqaba earthquake all along northern Algeria and Tunisia including the in 1995, Mw=7.3) as well as offshore Egypt in the eastern Tell and Atlas Mountains, in Tripoli, and Gulf Mediterranean Sea (i.e., the Alexandria earthquake in of Aqaba regions. In the same areas, displacement 1955, Ms=6.8; the Cyprus earthquake in 1996, Mw= peak values range from 2.0 to 16.2 cm. 6.8; the Ras El-Hekma earthquake in 1998, Mw=5.4; The maximum values obtained for DGA range Abou Elenean 2007). between 0.15 and 0.63 g and are located mainly in northern Algeria, Eastern Tunisia, around Tripoli in Libya, around the Gulf of Aqaba, and the entrance of 6 Conclusion the Gulf of Suez in Egypt (Fig. 9). The highest values are assigned to Chlef city and the surroundings The NDSHA maps in terms of Dmax, Vmax, and DGA reaching 0.63 g that is related to the 1980 El Asnam have been prepared for the NAF region. The analysis earthquake (Ms=7.3). In Morocco, maximum values and resulting maps obtained in this study represent the range between 0.154 and 0.3 g. They were obtained outcome of a mutual effort between the North African for Agadir and the Alhoceima regions, where the Group for Earthquake and Tsunami Studies (NAGET1) recent largest events of 28th February 1960 and 24th members and collaborators who took up the big chal- February 2004 occurred, respectively. The same range lenge of the homogenization and unification of different of values is computed for Cairo and surrounding areas data sources with the aim of assessing seismic hazard in in Egypt and throughout eastern Tell and Tunisian Atlas. Values ranging between 0.08 and 0.150 g are 1 http://naget.ictp.it/. J Seismol

North Africa using the first-order neo-deterministic (Algiers), carried on at the Geology Department of Abdelmalek method. This technique has already been used to pro- Essaadi University (Tangiers) in 2007 and recently at ENIT (Tunis) in 2012. It is a fruit of a collaborative effort of the first core of duce NDSHA maps for many areas of the world, among NASG members when the network was restricted to 15 scientists which are Morocco (Vaccari et al. 2001), Algeria and five countries only (Sudan has joined in 2010 and the number (Aoudia et al. 2000), and Egypt (El-Sayed et al. 2001). of NAGET (formerly NASG; see http://naget.ictp.it/)members The deterministic modeling of hazard for the Algeria increased to 136). This research benefited from the ICTP-OEA (Trieste) Programme in the framework of the North African Group territory, for example, yielded results validated by recent for Earthquake and Tsunami studies (NAGET) activities. The observations made in connection with events that oc- seismotectonic investigations were supported by the IGCP 601 curred after 2000. This is why it seemed to us essential project “Seismotectonics and Seismic Hazards of Africa.” The to apply that method to Tunisia and Libya too and to authors are indebted to the ICTP-SAND Group for making available algorithms, software and computational resources that made take this opportunity to update the seismic hazard maps this work possible. We are particularly grateful to Carlo Doglioni obtained previously in Morocco, Algeria, and Egypt to for his advices and comments about the structural geology and assess the seismic hazard not only at the scale of a geodynamics modeling of the study area. country but at the scale of a region: North Africa, which is one of the most earthquake-prone areas of the Mediterranean. The results obtained reflect our actual References state of knowledge (see ESM Online Resource). However, we draw the user’sattentionthatintheNAF Abou Elenean KM, Hussein HM, El-Ata A, Ibrahim EM (2000) region, some faults are poorly known (blind or offshore Seismological aspects of the Cairo earthquake, 12th October, 1992. Ann Geophys 43(3):485–504 faults in most of cases) and many seismogenic faults Abou Elenean KM (2007) Focal mechanisms of small and mod- remain unrecognized. The insufficiency of geological, erate size earthquakes recorded by the Egyptian National geophysical, and geodetic data as well as the character- Seismic Network (ENSN), Egypt. NRIAG J Geophys istics of some active faulting in North Africa led us to 6(1):119–153 Abou Elenean KM, Hussein HM (2007) Source mechanism and estimate the seismic hazard based only on information source parameters of May 28, 1998 earthquake. Egypt J from earthquakes. One should emphasize on the rele- Seismol 11:259–274 vance and need to integrate information about the ob- Ait Brahim L, Chotin P, Hinaj S, Abdelouafi A, Nakhcha C, served seismicity (i.e., from available earthquake cata- Dhont D, Sossey Alaoui F, Bouaza A, Tabyaoui H, Chaouni A (2002) Paleostress evolution in the Moroccan logues) with additional geological/geophysical evi- African margin from Triassic to present. Tectonophysics dences of the seismogenic potential of an area. The 357:187–205 NDSHA approach permits doing it in a very natural Ait Brahim L, Nakhcha C, Tadili B, El Mrabet A, Jabour N and straightforward way, as shown by Aoudia et al. (2004) Structural analysis and interpretation of the surface deformations of the Feb 24th 2004 Al Hoceima earthquake. (2000) and Panza et al. (2012, 2013). The relevance of CSEM-EMSC Newsl 21:10–12 such additional information, for reliable seismic hazard Aki K (1987) Strong motion seismology. In: Erdik M, Toksöz M assessment, is clearly demonstrated by Zuccolo et al. (eds) Strong motion seismology, NATO ASI Series, Series (2011). Therefore, we should increase our knowledge C: mathematical and physical sciences, vol. 204. D. Reidel Publishing, Dordrecht, pp 3–39 of both the distribution and rate of slip across active Akoglu AM, Çakir Z, Meghraoui M, Belabbès S, El Alami faults in North Africa. This is one objective of utmost SO, Ergintav S et al (2006) The 1994–2004 Al importance in NAGET activity. However, at this stage of Hoceima (Morocco) earthquake sequence: conjugate knowledge, we believe that the data we present in this fault ruptures deduced from InSAR. Earth Planet Sci Lett 252:467–480 paper may contribute to a better understanding of the Alasset PJ, Hébert H, Maouche S, Calbini V, Meghraoui M seismic hazard in North Africa. In addition to the seismic (2006) The tsunami induced by the 2003 Zemmouri earth- hazard assessment results, this paper presents the state of quake (Mw=6.9, Algeria): modelling and results. Geophys J the art on seismicity, tectonics, and seismic hazard in Int 166:213–226. doi:10.1111/j.1365-246X.2006.02912.x NAF covering five countries and could be very helpful Alvarez L, Vaccari F, Panza GF (1999) Deterministic seismic zoning of eastern Cuba. Pure Appl Geophys 156:469–486 for future research works. Ambraseys NN (1962) The seismicity of Tunis. Ann Geofis 15:233–244 Acknowledgments This work, dedicated to the memory of the Ambraseys NN, Melville CP, Adams RD (1994) The seismicity first coordinator of the North African Seismological Group of Egypt, Arabia and the Red Sea. A historical review. (NASG), the late Attia El-Sayed, started in 2005 at LBE-USTHB Cambridge University Press, Cambridge, 181 pp J Seismol

Ambraseys NN (1994) Material for the investigation of the Hoceima, Morocco earthquakes. Geophys J Int 166:1347– seismicity of Libya. Libyan Stud 25:7–22 1362 Aoudia A, Vaccari F, Suhadolc P, Meghraoui M (2000) Bommer JJ, Abrahamson NA (2006) Why do modern probabi- Seismogenic potential and earthquake hazard assessment listic seismic-hazard analyses often lead to increased haz- in the Tell Atlas of Algeria. J Seismol 4:79–88 ard estimates? BSSA 96(6):1967–1977 Ayadi A, Maouche S, Harbi A, Meghraoui M, Beldjoudi H, Bouhadad Y, Nour A, Laouami N, Belhai D (2003) The Beni- Oussadou F et al (2003) Strong Algerian earthquake strikes Ourtilane-Tachaouaft fault and seismotectonic aspects of near capital city. EOS Trans Am Geophys Union 84(50):561– the Babors region (NE of Algeria). J Seismol 7:79–88 568 Buforn E, Udias A, Colombas MA (1988) Seismicity, source Ayadi A, Dorbath C, Ousadou F, Maouche S, Chikh M, Bounif mechanisms and tectonics of the Azores–Gibraltar plate MA, Meghraoui M (2008) Zemmouri earthquake rupture boundary. Tectonophysics 152:89–118 zone (Mw 6.8, Algeria): aftershocks sequence relocation Buforn E, Sanz de Galdeano C, Udias A (1995) Seismotectonics of and 3D velocity model. J Geophys Res 113:B09301. the Ibero-Maghrebian region. Tectonophysics 248(247):261 doi:10.1029/2007JB005257 Buforn E, Coca P, Udías A, Lasa C (1997) Source mechanism of Baptista MA, Miranda JM, Chierici F, Zitellini N (2003) New intermediate and deep earthquakes in southern Spain. J study of the 1755 earthquake source based on multi- Seismol 1:113–130 channel seismic survey data and tsunami modelling. Nat Buforn E, Bezzeghoud M, Udias A, Pro C (2004) Seismic source Hazards Earth Syst Sci 3:333–340 in the Iberian–African plate boundary. Pure Appl Geophys Barazangi M, Fielding EJ, Isacks B, Seber D (1996) Geophysical 161(3):623–646 and geological databases and CTBT monitoring: a case study Bus Z, Szeidovitz G, Vaccari F (2000) Synthetic seismograms of the Middle East. In: Husebye ES, Dainty AM (eds) based deterministic seismic zoning for the Hungarian part Monitoring a comprehensive test ban treaty. Kluwer, of the Pannonian Basin. Pure Appl Geophys 157:205–220 Dordrecht, pp 197–224 Calvert A, Gomez F, Dogan S, Barazangi M, Jabour N, Iben Belabbès S, Meghraoui M, Çakir Z, Bouhadad Y (2009a) Brahim A, Demnati AD (1997) An integrated geophysical InSAR analysis of a blind thrust rupture and related active investigation of recent seismicity in the Al-Hoceima region folding: the 1999 Ain Temouchent earthquake (Mw 5.7, of North Morocco. Bull Seismol Soc Am 87(3):637–651 Algeria) case study. J Seismol 13:421–432. doi:10.1007/ Calvert A, Sandvol E, Seber D, Barazangi M, Vidal F, Alguacil s10950-008-9135-x G, Jabour N (2000a) Propagation of regional seismic Belabbès S, Wicks C, Ziyadin C, Meghraoui M (2009b) Rupture phases (Lg and Sn) and Pn velocity structure along the parameters of the 2003 Zemmouri (Mw 6.8), Algeria, earth- Africa–Iberia plate boundary zone: tectonic implications. quake from joint inversion of interferometric synthetic Geophys J Int 142:348–408 aperture radar, coastal uplift, and GPS. J Geophys Res Calvert A, Sandvol E, Seber D, Barazangi M, Roecker S, 114:B03406. doi:10.1029/2008JB005912 Mourabit T, Vidal F, Alguacil G, Jabour N (2000b) Beldjoudi H, Guemache MA, Kherroubi A, Semmane F, Yelles- Geodynamic evolution of the lithosphere and upper mantle Chaouche AK, Djellit H, Amrani A, Haned A (2009) The beneath the Alboran region of the western Mediterranean: Lâalam (Béjaïa, north-east Algeria) moderate earthquake constraints from travel time tomography. J Geophys Res (Mw=5.2) on March 20, 2006. Pure Appl Geophys 105:10871–10898 166:623–640. doi:10.1007/s00024-009-0462-9 Castaños H, Lomnitz C (2002) PSHA: is it science? Eng Geol Benouar D (1994) Materials for the investigation of the seismic- 66:315–317 ity of Algeria and adjacent regions during the twentieth Çakir Z, Meghraoui M, Akoglu AM, Jabour N, Belabbes S, Aït century. Ann Geofis 37(4):459–860 Brahim L (2006) Surface deformation associated with the Mw Benouar D, Aoudia A, Maouche S, Meghraoui M (1994) The 18 6.4, 24 February 2004 Al Hoceima, Morocco, earthquake August 1994 Mascara (Algeria) earthquake—a quick-look deduced from InSAR: implications for the active tectonics report. Terra Nova 6:634–637 along North Africa. Bull Seismol Soc Am 96(1):59–68 Benouar D (1996) Seismic hazard evaluation at Algiers Cherkaoui Maknassi MT (1991) Contribution à l’étude de l’aléa using Benouar’searthquakecatalogue.NatHazard sismique au Maroc. Thèse de doctorat de l’université 13:119–131 Joseph fourier de Grenoble, France Benouar D, Molas G, Yamazaki F (1996) Earthquake hazard Cochron JR (2005) The northern Red Sea: nucleation of an mapping in the Maghreb countries: Algeria, Morocco, oceanic spreading center within a continental rift. Tunisia. Earthq Eng Struct Dyn 25:1151–1164 Geochem Geophys Geosyst 6:Q03006. doi:10.1029/ Benouar D (2005) Earthquake risk in Africa: a community 2004GC000826 leader’s guide. UN/ISDR/, Africa Corti G, Cuffaro M, Doglioni C, Innocenti F, Manetti P (2006) Bezzeghoud M, Buforn E (1999) Source parameters of the 1992 Coexisting geodynamic processes in the Sicily Channel. In: Melilla (Spain, Mw=4.8), 1994 Al Hoceima (Morocco, Mw Dilek Y, Pavlides S (eds) Postcollisional tectonics and =5.8) and Mascara (Algeria, Mw=5.7) earthquakes and magmatism in the Mediterranean region and Asia. seismotectonic implications. Bull Seismol Soc Am Geological Society of America Special Paper, 409, pp 89:359–372 83–96 Biggs J, Bergman E, Emmerson B, Funning JG, Jackson J, Cornell CA (1968) Engineering seismic risk analysis. Bull Parsons B, Wright TJ (2006) Fault identification for buried Seismol Soc Am 58:1583–1606 strike-slip earthquakes using InSAR: the 1994 and 2004 Al DeMets C, Gordon R, Argus D, Stein S (1990) Effect of recent J Seismol

revisions to the geomagnetic reversal time scale on Hamdache M, Bezzeghoud M, Mokrane A (1998) Estimation of estimates of current plate motions. Geophys Res Lett seismic hazard parameters in the northern part of Algeria. 21(20):2191–2194 Pure Appl Geophys 151:101–117 Dewey JF, Helman ML, Turco E, Hutton DWH, Knott SD Hamdache M, Retief SJP (2001) Site-specific seismic hazard (1989) Kinematics of the western Mediterranean. In estimation in the main seismogenic zones of North Algeria. Coward MP et al. (eds) Alpine tectonics. Geological Pure Appl Geophys 158:1677–1690 Society of London Special Publication 45, pp 265–283 Hamouda AZ (2011) Assessment of seismic hazards for Du ZJ, Michelini A, Panza GF (1998) EurI D: a regionalized 3- Hurghada, Red Sea, Egypt. Nat Hazards 59:465–479 D seismological model of Europe. Phys Earth Planet Int Harbi A, Benouar D, Benhallou H (2003a) Re-appraisal of 105:31–62 seismicity and seismotectonics in the north-eastern El Alami SO, Tadili B, Ait Brahim L, Mouayn I (2004) Algeria. Part I: Review of historical seismicity. J Seismol Seismicity of Morocco for the period 1987–1994. Pure 7:115–136 Appl Geophys 161:969–982 Harbi A, Maouche S, Benhallou H (2003b) Re-appraisal of seis- El Fiky GS (2000) Crustal strains in the Eastern Mediterranean micity and seismotectonics in the north-eastern Algeria. Part and Middle East as derived from GPS observations. Bull II: 20th century seismicity and seismotectonics analysis. J Earthq Res Inst Univ Tokyo, Japan 75(2):161–181 Seismol 7:221–234 El-Gamili M (1982) A geophysical interpretation of a part of the Harbi A, Maouche S, Vaccari F, Aoudia A, Oussadou F, Panza Nile Valley, Egypt based on gravity data. J Geol 2:101–120 GF, Benouar D (2007) Seismicity, seismic input and site El Mrabet T (2005) The great earthquakes in the Maghreb effects in the Sahel-Algiers region (North-Algeria). SDEE region and their consequences on man and environment. 27(5):427–447 Edit. Centre National de Recherche Scientifique et Harbi A, Peresan A, Panza GF (2010) Seismicity of eastern Technique, Rabat, 451 pp (in Arabic with abstract in Algeria: a revised and extended earthquake catalogue. English) Nat Hazards 54:724–747. doi:10.1007/s11069-009-9497-6 El-Mozoughi SA, Suleiman A (2000) Effective elastic thickness Harbi A, Meghraoui M, Maouche S (2011) The Djidjelli of the lithosphere and mechanism of isostatic compensa- (Algeria) earthquakes of 21 and 22 August (I0 IX, VIII) tion in Libya. 5th International Conference on the Geology and related tsunami effects revisited. J Seismol 15(1):105– of the Arab World, Cairo University, pp 1077–1084 129. doi:10.1007/s10950-010-9212-9 El-Sayed A, Wahlström R, Kulhánek O (1994) Seismic hazard Hatzfeld D (1978) Etude sismotectonique de la zone de collision of Egypt. Nat Hazard 10(3):247–259 Ibéro-Maghrébine. Thèse de Doctorat d’Etat, Université El-Sayed AM, Vaccari F, Panza GF (2001) Deterministic seis- Scientifique et Médicale de Grenoble, 281 pp mic hazard in Egypt. Geophys J Int 144(3):555–567 Hussein HM, Marzouk I, Moustafa AR, Hurukawa N (2006) Fadil A, Vernant P, McClusky S, Reilinger R, Gomez F, Ben Preliminary seismicity and focal mechanisms in the south- Sari D, Mourabit T, Feigl K, Barazangi M (2006) Active ern Gulf of Suez, August 1994 through December 1997. J tectonics of the western Mediterranean: geodetic evidence Afr Earth Sci 45:48–60 for rollback of a delaminated subcontinental lithospheric Hussein HM, Abou Elenean KM, Marzouk IA, Peresan A, slab beneath the Rif Mountain (Morocco). Geology Korrat IM, Abu El-Nader E, Panza GF, El-Gabry MN 34(7):529–532 (2008) Integration and magnitude homogenization of the Frizon de Lamotte D, Saint-Bezar B, Bracène R, Mercier E (2000) Egyptian earthquake catalogue. Nat Hazards 47:525–546 The two steps of the Atlas building and geodynamics of the Klügel JU (2007) Error inflation in probabilistic seismic hazard western Mediterranean. Tectonics 19:740–761 analysis. Eng Geol 90:186–192 Girardin N, Hatzfeld D, Guiraud R (1977) La sismicité du Nord Korrat IM, El Agami NL, Hussein HM, El Gabry MN (2005) de l’Algérie. CR Somm Soc Géol Fr Fasc 2:95–100 Seismotectonics of the passive continental margin of Giardini D, Grünthal G, Shedlock KM, Zhang P (1999) The Egypt. J Afr Earth Sci 41:145–150 GSHAP global seismic hazard map. Ann Geofis 42(6):1225– Kossobokov VG, Maeda K, Uyeda S (1999) Precursory activa- 1228 tion of seismicity in advance of Kobe, 1995 M=7.2 earth- Gomez F, Beauchamp W, Barazangi M (2000) Role of the Atlas quake. Pure Appl Geophys 155:409–423 Mountains (northwest Africa) within the African–Eurasian Kossobokov VG, Nekrasova AK (2012) Global seismic haz- plate-boundary zone. Geology 28:775–778 ard assessment program maps are erroneous. ISSN Gracia E, Danobeitia J, Verges J, The Parsifal Team (2003) 07479239, Seismic Instruments, 2012, Vol. 48, No. 2, Mapping active faults offshore Portugal (36°N–38°N): im- pp. 162–170. © Allerton Press, Inc., 2012.Original plications for seismic hazard assessment along the south- Russian Text © V.G. Kossobokov, A.K. Nekrasova, west Iberian margin. Geology 31:83–86 2011, published in Voprosy Ingenernoy Seismologii, Gueguen E, Doglioni C, Fernandez M (1998) On the post 25 Ma 2011, vol. 38, no. 1, pp. 65–76) geodynamic evolution of the western Mediterranean. Koulali A, Ouazar D, Tahayt A, King RW, Vernant P, Reilinger Tectonophysics 298:259–269 RE, McClusky S, Mourabit T, Davila JM, Amraoui N Guidoboni E, Comastri A, Traina G (1994) Catalogue of the (2011) New GPS constraints on active deformation along ancient earthquakes in the Mediterranean area up to the the Africa–Iberia plate boundary. Earth Planet Sci Lett 10th century. Istituto Nazionale di Geofisica, Rome, 504 pp 308:211–217 Gusev AA (1983) Descriptive statistical model of earthquake Krinitzsky EL (1998) The hazard in using probabilistic seismic source radiation and its application to an estimation of short hazard analysis for engineering. Environ Eng Geosci period strong motion. Geophys J R Astron Soc 74:787–800 4(4):425–443 J Seismol

Laouami N, Slimani A, Bouhadad Y, Chatelain JL, Nour A OAGS–IGCP Project 601 Meeting «Seismotectonics (2006) Evidence for fault-related directionality and local- and seismic hazards in Africa», Windhoek 2011, ized site effects from strong motion recordings of the 2003 Abstracts volume, p 1 Boumerdes (Algeria) earthquake: consequences on damage Meghraoui M, Pondrelli S (2012) Active faulting and distribution and the Algerian seismic code. Soil Dyn transpression tectonics along the plate boundary in North Earthq Eng 26:991–1003 Africa. Ann Geophys 55:5. doi:10.4401/ag.4970 Lee S, Marone F, Meijde M, Giardini D, Deschamps A, Margheriti Michard A, Chalouan A, Feinberg H, Goffe B, Montigny R L, Burkett P, Solomon SC, Alves PM, Chouliaras M, (2002) How does the Alpine belt between Spain and Eshwehdi A, Suleiman A, Gashut H, Herak M, Ortiz R, Morocco? Bull Soc Géol Fr 173:3–15 Martin Davila J, Ugalde A, Vila J, Yelles K (2001) New Morel JL, Meghraoui M (1996) Goringe–Alboran–Tell tectonic seismographic data from the Eurasia–Africa plate boundary zone: a transpression system along the Africa–Eurasia plate region. EOS Transactions, American Geophysical Union boundary. Geology 24:755–758 82:637–646 Nocquet JM, Calais E (2004) Crustal velocity field of Western Maamoun M, Megahed A, Allam A (1984) Seismicity of Egypt. Europe from permanent GPS array solutions, 1996–2001. HIAG Bull 4(Ser. B):109–160 Geophys J Int 154:72–88 Mahmoud S, Reilinger R, McClusky S, Vernant P, Tealeb A Nyblade A, Suleiman I, Roy R, Pursell B, Suleiman A, Doser D, (2005) GPS evidence for northward motion of the Keller G (1996) Terrestrial heat flow in Sirt Basin, Libya Sinai block: implications for E. Mediterranean tecton- and the pattern of heat flow across northern Africa. J ics. Earth Planet Sci Lett 238:217–227 Geophys Res 101(B8):17737–17746 Maouche S, Harbi A, Meghraoui M (2008) Attenuation of Ouyed M, Meghraoui M, Cisternas A, Deschamps A, Dorel intensity for the Zemmouri earthquake of 21 May 2003 J, Fréchet J, Gaulon R, Philip H (1981) (Mw 6.8): insights for the seismic hazard and historical Seismotectonics of the El Asnam earthquake. Nature earthquake sources in northern Algeria. In: Fréchet J, 292:26–31 Meghraoui M, Stuchi M (eds) Historical seismology, Panza GF (1985) Synthetic seismograms: the Rayleigh waves interdisciplinary studies of past an recent earthquakes. model summation. J Geophys 58:125–145 Springer, New York, pp 327–350 Panza GF, Vaccari F, Costa G, Suhadolc P, Fäh D (1996) Marillier FJY (1981) Upper mantle structure of the Euro- Seismic input modeling for zoning and microzoning. African plate contact between the Mid-Atlantic Ridge Earthquake Spectra 12:529–566 and the Western Mediterranean sea from seismic surface Panza GF, Vaccari F, Cazzaro R (1999) Deterministic seismic waves and body waves. PhD thesis, E. T. H. Zurich, hazard assessment. In: Wenzel et al. (eds) Vrancea earth- 287 pp quake: tectonics, hazard and risk mitigation. Kluwer, Markusic S, Suhadolc P, Herak M, Vaccari F (2000) A contribu- Olanda, pp 269–286 tion to seismic hazard in Croatia from deterministic model- Panza GF, Romanelli F, Vaccari F (2001) Seismic wave propa- ling. Pure Appl Geophys 157:185–204 gation in laterally heterogeneous anelastic media: theory Marzouk I (1995) Engineering seismological studies for and applications to seismic zonation. Adv Geophys 43:1– foundation rock for El-Giza Province. NRIAG Bull 95 11:265–296 Panza GF et al (2002) Realistic modelling of seismic input for McClusky S, Reilinger R, Mahmoud S, Ben Sari D, Tealeb A megacities and large urban areas, the UNESCO-IUGS- (2003) GPS constraints on Africa (Nubia) and Arabia plate IGCP project 414. Episodes 25(3):160–184 motions. Geophys J Int 155:126–138 Panza GF, Romanelli F, Vaccari F, Decanini L, Mollaioli F Medina F, Cherkaoui TE (1991) Focal mechanisms of the Atlas (2003) Seismic ground motion modelling and damage earthquakes and tectonic implications. Int J Earth Sci earthquake scenarios, a bridge between seismologists and 80(3):639–648 seismic engineers. OECD Workshop on the Relations be- Meghraoui M (1991) Blind reverse faulting system associated tween Seismological DATA and Seismic Engineering, with the Mont Chenoua-Tipaza earthquake of 29 October Istanbul, 16–18 October 2002, NEA/CSNI/R (2003) 18, 1989 (north-central Algeria). Terra Nova 3:84–93 pp 241–266 Meghraoui M, Doumaz F (1996) Earthquake-induced flooding Panza GF, Irikura K, Kouteva M, Peresan A, Wang Z, Saragoni R and paleoseismicity of the El Asnam (Algeria) fault-related (2011) Advanced seismic hazard assessment. Pure Appl. fold. J Geophys Res 101:17617–17644 Geophys 168:1–9. doi:10.1007/s00024-010-0179-9 Meghraoui M, Maouche S, Chemaa B, Çakir Z, Aoudia A, Panza GF, La Mura C, Peresan A, Romanelli F, Vaccari F (2012) Harbi A, Alasset PJ, Ayadi A, Bouhadad Y, Benhamouda Seismic hazard scenarios as preventive tools for a disaster F (2004) Coastal uplift and thrust faulting associated with resilient society. Adv Geophys 53:93–165. doi:10.1016/ the Mw=6.8 Zemmouri (Algeria) earthquake of 21 May B978-0-12-380938-4.00003-3, ISSN: 0065–2687 2003. Geophys Res Lett 31:L19605. doi:10.1029/ Panza GF, Peresan A, La Mura C (2013) Seismic hazard 2004GL020466 and strong ground motion: an operational neo- Meghraoui M (2011a) The seismotectonic characteristics of deterministic approach from national to local scale. the African plate: a cornerstone for a realistic seismic Encyclopedia of Life Support Systems (EOLSS). hazard assessment. 23rd Colloquium of African UNESCO (in press) Geology, January 8–14, 2011, Abstracts volume, p 270 Parvez I, Vaccari F, Panza GF (2003) A deterministic seismic Meghraoui M (2011b) Building the seismotectonic map of hazard map of India and adjacent areas. Geophys J Int Africa: procedure, implications and perspectives. 2003(155):489–508 J Seismol

Pelaez JA, Hamdache M, López Casado C (2003) Seismic hazard Sieberg A (1932). Erdbeben geographie. Handbuch der in Northern Algeria using spatially smoothed seismicity. Geophysik, 4, pp 687–1005, Berlin Results for peak ground acceleration. Tectonophysics Stiros SC (2001) The AD 365 Crete earthquake and possible 372:105–119. doi:10.1016/S0040-1951(03)00234-8 seismic clustering during the fourth to sixth centuries AD in Pelaez JA, Hamdache M, Lopez Casado C (2005) Updating the the Eastern Mediterranean: a review of historical and archae- probabilistic seismic hazard values of northern Algeria with ological data. J Struct Geol 23:545–562. doi:10.1016/S0191- the 21 May 2003 M 6.8 Algieers earthquake included. Pure 8141(00)00118-8 Appl Geophys 162:2163–2177 Tahayt A, Mourabit T, Rigo A, Feigl KL, Fadil A, McClusky S, Pelaez JA, Hamdache M, Casado CL (2006) Seismic hazard in Reilinger R, Serroukh M, Ouazzani-Touhami A, Ben-Sari D, terms of spectral accelerations and uniform hazard spectra Vernant P (2008) Mouvements actuels des blocs tectoniques in northern Algeria. Pure Appl Geophys 163:119–135 dans l'arc Bético-Rifain à partir des mesures GPS entre 1999 Pelaez JA, Chourak M, Tadili BA, Aït Brahim L, Hamdache M, et 2005. CR Geosci 340:400–413 Lopez Casado C, Martinez Solares JM (2007) A catalog of Tahayt A, Feigl KL, Mourabit T, Rigo A, Reilinger R, main Moroccan earthquakes from 1045 to 2005. Seismol McClusky S, Fadil A, Berthier E, Dorbath L, Serroukh Res Lett 78:614–621 M, Gomez F, BenSari D (2009) The Al Hoceima Peresan A, Harbi A, Hussein HM, Ogwari OP, Panza GF (2009) (Morocco) earthquake of 24 February 2004, analysis and Toward the compilation of a unified earthquake catalogue interpretation of data from ENVISAT ASAR and SPOT5 for North Africa. IASPEI Assembly, 10–16 January, Cape validated by ground-based observations. Remote Sens Town, South Africa Environ 113(2):306–316. doi:10.1016/j.rse.2008.09.015 Peresan A, Ogwari OP (2010) Preliminary compilation of a uni- Turki H (1990) Etat de la Sismicité Historique en Tunisie. fied earthquake catalogue for North Africa. The Abdus Salam Proceeding of the Workshop on Historical Seismicity and International Centre for Theoretical Physics, ICTP, Trieste, Seismotectonics of the Mediterranean Region, Istanbul, p. Internal Report IC/IR/2010/004 3246328 Polidori R, Di Vita A, Evrard G, Bacchielli L (1999) Libya the lost Udias A, Buforn E (1991) Regional stresses along the Eurasia– cities of the Roman Empire. Könemann, Cologne, 256 pp Africa plate boundary derived from focal mechanisms of large Reilinger R, McClusky S, Vernant P, Lawrence S, Ergintav S, earthquakes. Pure Appl Geophys 136:433–448. doi:10.1007/ Cakmak R, Ozener H, Kadirov F, Guliev I, Stepanyan R, BF00878580 Nadariya M, Hahubia G, Mahmoud S, Sakr K, ArRajehi A, Vaccari F, Tadili B, El Qadi A, Ramdani M, Ait Brahim M, Paradissis D, Al-Aydrus A, Prilepin M, Guseva T, Evren E, Limouri M (2001) Deterministic seismic hazard assess- Dmitrotsa A, Filikov SV, Gomez F, AlGhazzi R, Karam G ment for North Morocco. JSEE 3(1):1–12 (Summer) (2006) GPS constraints on continental deformation in the Vita-Finzi C (2010) Letter from Libya: epigraphy and land- Africa–Arabia–Eurasia continental collision zone and im- scape. Antiquity 84:558–561 plications for the dynamics of plate interactions. J Geophys Vogt J (1993) Further research on the historical seismicity of Res 111:BO5411. doi:10.1029/2005JB004051 Tunisia. Terra Nova 5:475–476 Roussel J (1973) Les zones actives et la fréquence des séismes en Wang Z (2011) Seismic hazard assessment: issues and alterna- Algérie 1716–1970. Bull Soc Hist Nat Afr Nord 64(3):11–227 tives. Pure Appl Geophys 168:11–25. doi:10.1007/s00024- Rothé JP (1970) Mission d'information séismologique, Moyen- 010-0148-3 Orient et Afrique du Nord, novembre-décembre 1969. Wyss M, Nekrasova A, Kossobokov V (2012) Errors in UNESCO Report No. de série: 1759/BMS. RD/SCF, Paris expected human losses due to incorrect seismic hazard Ruegg JC, Kasser M, Tarantola A, Lepine JC, Chouikrat B (1982) estimates. Nat Hazard 62(3):927–935. doi:10.1007/ Deformations associated with the El Asnam earthquake of 10 s11069-012-0125-5 October 1980: geodetic determination of vertical and hori- Xie J, Mitchell BJ (1990) A back-projection method for zontal movements. Bull Seism Soc Am 72(6):2227–2244 imaging large-scale lateral variations of Lg coda Q Salamon A, Hofstetter A, Garfunkel Z, Ron H (2003) with application to continental Africa. Geophys J Int Seismotectonics of the Sanai subplate—the eastern 100:161–181 Mediterranean region. Geophys J Int 155:149–173 Zilberman E, Amit R, Porat N, Avner U (1998) Relocation of Serpelloni E, Vannucci G, Pondrelli S, Argnani A, Casula G, the epicenter of the 1068 earthquake in the Avmona Playa, Anzidei M, Baldi P, Gasperini P (2007) Kinematics of the southern Dead Sea rift, using paleoseismic and western Africa–Eurasia plate boundary from focal mecha- archeoseismic evidence. Abstracts of the 26th General nisms and GPS data. Geophys J Int 169(3):1180–1200. Assembly of the European Seismological Conference, doi:10.1111/j.1365-246X.2007.03367.x August 23–28 Suleiman A, Doser D (1995) Seismicity, seismotectonics and Zivcic P, Suhadolc P, Vaccari F (2000) Seismic zonation of earthquake hazards of Libya, with detailed analysis of the Slovenia based on deterministic hazard computation. Pure April 19, 1935, M=7.1 earthquake sequence. Geophys J Int Appl Geophys 157:171–184 120:312–322 Zuccolo E, Vaccari F, Peresan A, Panza GF (2011) Neo- Suleiman A, Albini P,Migliavacca P (2004) A short introduction to deterministic and probabilistic seismic hazard assessments: historical earthquakes in Libya. Ann Geophys 47(2/3):545– a comparison over the Italian Territory. Pure Appl Geophys 554 168:69–83